Melloni is a young girl who appears to be around seven years old.[1] She is seen wearing purple clothing and accessories, and she sleeps with a teddy bear under a purple blanket.[1] She has brown hair worn in pigtails and tan skin like that of her parents; her mother is ethnically Kerztian.[1]

Melloni is seen living in Kezare in Lossand with her parents, who sometimes call her "Melly".[1][2] She appears to be aware of her mother's dangerous profession as a trackt, as she sometimes worries that Ais will not come home.[1] Ais often receives death threats that include her family;[1] after she is assigned to be Kenton's bodyguard, she and Mellis agree that the possibility of someone acting on those threats has increased, and that Mellis and Melloni need to relocate to an undisclosed location.[2]